Employee Benefit Plans - Summary of amounts recognized in consolidated balance sheets (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Long-term pension liability	$ (34,399)	$ (21,966)
Retirement Income Plan
Defined Benefit Plan Disclosure [Line Items]
Funded status	(14,788)	(5,102)
SERP liability	(19,611)	(16,864)
Long-term pension liability	$ (34,399)	$ (21,966)